So we started this project in July knowing nothing about Airstreams other than how to spell the name. We towed it 400 miles home after checking bearings, brakes etc. Tires looked ok, held air and PO claimed they were only 2 years old. We've been really busy on the interior and other mechanicals (such as plumbing, electric, weatherstripping, leak stopping etc). We are planning on going places this summer am preparing to order axles and replace tires. I went outside to double check the size on the tires (I haven't really looked at them much) at was worried to see a "P" in front of 22575R15. They are goodyears, but passanger tires. We're replacing axles next, hopefully ordering those in about 3-4 weeks and want to replace tires and shocks at the same time. My worry is, after reading posts about people using the wrong ply tires (i.e. 8 instead of 6) are the original rims more than likely now unsafe for 6 ply tires? The trailer isn't going anywhere until new axles and tires are on, but we really wanted to paint and reuse the original rims that have all the clips and original baby moon caps intact.

If the tire you have had on the trailer were 6 ply, you "cannot" change them to a higher rating.

To do so will split every wheel you use them on.

This is as per "every wheel manufacturer."

If you want to use 8 ply, that's fine, but you must change the wheels.

You must not ever use 10 ply wheels for an Airstream trailer.

Case in point. One of our customers was told not to put 8 ply tires on wheel that had 6 ply tires on them for years.

He said "BS." and left in a huff.

He went to a local dealer and in fact did install the 8 ply tires.

He called us from Phoenix, some 350 miles away, after a couple of days. He said "he should have listened, as he replace three of his wheels already, because they indeed split, just like he was told they would."

To make a long story even longer, the reason behind these statements were the higher inflation pressures normally associated with 8 ply (D rating) tires, rather than the lower 6 ply (C rating) tires.
The original wheels may only have been rated at the 6 ply pressure, which is 50psi. Since the wheels were built before any kind of labeling was put on the wheels, you have no way of really knowing what the original wheels rating (8 or 6 ply) was. 8 ply (D rating) has a pressure of 65psi. The higher pressure could cause internal stresses in the wheels, resulting in stress fractures.
Sooo, if your wheels have 8 ply tires on them, and have not failed, you can safely replace them in-kind. Since your wheels have passenger car tires on them (4 ply, or 32-35psi pressure), you should not put D rated tires on them. If for some reason you have to use D rated tires, inflate them to the lower (50psi) pressure. IIRC, the smaller coaches, such as Tradewinds and Safaris, and even some Overlanders, specified C load range tires anyway.

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Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
Terry

To make a long story even longer, the reason behind these statements were the higher inflation pressures normally associated with 8 ply (D rating) tires, rather than the lower 6 ply (C rating) tires.
The original wheels may only have been rated at the 6 ply pressure, which is 50psi. Since the wheels were built before any kind of labeling was put on the wheels, you have no way of really knowing what the original wheels rating (8 or 6 ply) was. 8 ply (D rating) has a pressure of 65psi. The higher pressure could cause internal stresses in the wheels, resulting in stress fractures.
Sooo, if your wheels have 8 ply tires on them, and have not failed, you can safely replace them in-kind. Since your wheels have passenger car tires on them (4 ply, or 32-35psi pressure), you should not put D rated tires on them. If for some reason you have to use D rated tires, inflate them to the lower (50psi) pressure. IIRC, the smaller coaches, such as Tradewinds and Safaris, and even some Overlanders, specified C load range tires anyway.

Terry,

Thanks, your explanation makes sense. It is higher inflation pressure on the tires and not the tires which make the difference.

our only option locally for goodyear's is the sears tire center (only dealer in 100 miles). They don't stock but priced me 4 22575r15 C load marithons for 103 each plus mounting tax etc. Are passanger tires a higher number ply than trailer tires? no readable data on the tires themselves.

The radial trailer tires are ST tires, which means, suprrisingly, Special Trailer. They have different compounds which allow them to flex and, well, trail, better than P (passenger) or LT (light truck) tires. They also don't have the same traction characteristics as tires that would be placed on a motorized vehicle. Also, passenger car tires are typically load range B, or 4 ply rated.
Trailer tires are not required to display the UTQG (uniform tire quality grade) which consists of temperature ratings, straight line braking (traction) ratings, and treadwear ratings.

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Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
Terry

wow thanks Terry, thats a lot of great info. So the issue with trailers using a passenger tire (besides tread etc) is that they are likely under rated for my trailer if I understand correctly (B vs C or D). I appreciate the info and hopefully we're good to go with new rubber, axles/brakes/shocks here very soon.

Hi, I want to add one more thing for you to think about; Someone else posted this. [not my experience] Buy your axles first, because you may have to buy different wheels to fit the new hubs. I believe they said that "Never Lube Bearings" need a larger center hole in the wheel and their original wheels would not fit.

If you are looking to get ST (trailer tires) then the most likely choices are Goodyear Marathons or Carlisle's. One thing to keep in mind is the speed at which you plan on traveling. ST tires are rated to go a maximum of 65 mph at their maximum psi rating at the max load.

What this means is that a load range C tire carrying 2150 lbs (its max load) at 50 psi (its max psi) can go a maximum of 65 mph. If you plan on going 66 - 75 mph you have to increase the tire psi by 10 lbs, which you cannot do because it's at it's max psi. ST225/75*15 as an example.

If it were a load range D tire you could do this because it's max load is 2540 lbs at 65 psi. Consult your load limit vs tire inflation chart to see what pressure your tire needs to be at for your load. If your load lets you run a lower psi then you can increase it.

Two things to note. Increasing the tire pressure 10 lbs reduces the load carrying capacity by 10% and it is not recommended to drive at elevated speeds constantly.

The maximum speed for a truck with trailer in California is 55 mph. Good luck doing that. I don't recommend speeding, but some times you have to do it.

got it, yeah I've never had it over 60 mph, not sure I'd want to. We basically want the best quality tire we can afford. We're ordering our axles through Andy, just want a good smooth riding trailer that's safe and doesn't rip itself apart. Thanks for all the info.

got it, yeah I've never had it over 60 mph, not sure I'd want to. We basically want the best quality tire we can afford. We're ordering our axles through Andy, just want a good smooth riding trailer that's safe and doesn't rip itself apart. Thanks for all the info.

If you are getting your axles from Inland Andy, your wheels will fit the axles. Also, since you are buying your axles from him, he does sell OEM style steel wheels that will accept the load range D tires. MAYBE he would cut you a deal on a set. It never hurts to ask, and then you won't have to worry about the wheels maybe coming apart on you.

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Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
Terry

I want to thank you for your information. I have old rims with clips, but I do not have baby moons. The rims are not split rims, but they are old and rusty.
I also have new axles from Inland RV. My tires are rated for 65psi and I so far have not had any problems with my rims. But I will be buying new rims because I do not want to take the chance. Again, thank you

placed an order at Inland for 2 3000 lb'ers loaded, know what I'm doing this Saturday? If there are any really cool tricks that the average back yard mechanic wouldn't know about the switchover (besides driving up on blocks) I'd love to hear it. Axles are supposed to be here Friday. Any help appreciated.